//遍历多维数组方法实现

Array.prototype.each = function (fn) {

    try {

        //定义计数器

        const ZERO = 0;

        this.i = ZERO;

        //判断数组非空且参数的构造器为函数

        if (this.length > this.i && fn.constructor === Function) {

            while (this.length > this.i) {

                var item = this[this.i];

                //如果当前元素是数组

                if (item && item.constructor === Array) {

                    if (item.length > ZERO) {

                        item.each(fn);

                    } else {

                        //空数组显示"[]", 而非空白

                        fn.call(item, "[]");

                    }

                } else {//当前元素非数组,此处扩展遍历对象,以键值对方式显示，而非[object Object]

                    if (item && typeof item === "object") {

                        //非空对象

                        if (Object.keys(item).length > ZERO) {

                            for (const key in item) {

                                fn.call(item, key + " : " + item[key]);

                            }

                        } else {

                            //空对象

                            fn.call(item, "{}");

                        }

                    } else {//其余元素，包括对象类型的null

                        fn.call(item, item);

                    }

                }

                this.i++;

            }

            //销毁计数器，回收内存

            delete this.i;

        }

    } catch (e) {

        console.log("error happened in printing multiple-dimension array. error message : " + e);

        throw e;

    }

    return this;

};

var array = ["中国", "Charles", 0, ["A", "B", "C"], ["D", ["E", "F"], "G"], {

    name: "ITACHI",

    gander: "Male"

}, [], null, undefined, false];

//遍历多维数组

array.each(function (item) {

    alert(item);

});

//遍历一维数组

/*array.forEach(function (item, index, arr) {

    alert(item);

});*/